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Translation of abstract (English)

The formation of massive bound stellar clusters in molecular clouds is a race between efficient star formation and energetic feedback processes by high mass stars, which cancel star formation and expel the residual gas. The influence of gas expulsion on the dynamical evolution of star forming regions, initially consisting of a bound system of stars and gas, is investigated. Collisionless numerical N-body calculations were performed, describing the gas expulsion by a time variable external potential. Bound clusters will only result, if the star formation efficiency is considerably higher than the typical observed efficiencies in the Galaxy, if the gas expulsion timescale is several times longer than the dynamical timescale or if the system initially is not in virial equilibrium. Therefore the formation of clusters from initially cold turbulent molecular clouds is investigated, using smoothed particle hydrodynamics with an idealized star formation description. Stars are treated as collisionless N-bodies and feedback is implemented by thermally heating the surrounding medium. In the collapsing and fragmenting molecular cloud the star formation efficiency and thus the boundness of the resulting system strongly depends on the time delay between the formation of stars and the time when feedback from the stars begins and on a chosen global density criterion, which determines when stars form during the collapse of the cloud.